Look at this video, it explains static timing, and it's the same for any kind of vehicle that has points. You may have left out one of the pieces that isolates the moving point and if that is touching the post, the whole plate will have voltage. It when the point closes that the charge in the coil goes to the distributor (coils) and causes a spark. It seems that you have you voltage touching the plate somewhere, it could even be a pinched wire. 